马占相思树皮单宁含量的影响因素研究

研究了产地、树龄、部位以及贮存时间对马占相思树皮单宁含量的影响。结果表明：不同产地的该种树皮的单宁含量差异较大；树龄对树皮的单宁含量影响较明显，随着树龄的增加，单宁含量逐渐减少；从主干的根部往顶部，树皮的单宁含量逐渐降低，非单宁含量逐渐增加；贮存时间的延长，单宁含量减少，因此，贮存时间不能过长。研究结果表明马占相思树皮是适合工业生产的一种优良栲胶原料。     

桉树皮单宁分析

对广西高峰林场桃源分厂4年生的大叶桉和尾叶桉树皮的单宁含量进行了分析,并分别进行了栲胶的试制。分析结果表明:大叶桉和尾叶桉树皮单宁属于缩合类单宁,树皮单宁含量分别为7.6%和7.8%,纯度分别为67.9%和70.3%;大叶桉树皮栲胶单宁含量为65.4%,尾叶桉树皮栲胶单宁含量为63.3%。桉树皮可作为新品种栲胶原料,其栲胶值得推广应用。     

广西不同产地板栗壳斗的分析

采用LY/T 1083-2008栲胶原料分析试验方法,对广西不同产地及不同品种的板栗壳斗的总抽出物、单宁、总颜色进行了分析测定。结果表明,同一品种不同产地及不同品种板栗壳斗的总抽出物、单宁、总颜色值有一定差异,其中单宁含量差异不大,总抽出物和总颜色值差异较大。板栗壳斗平均总抽出物为31.7%、单宁18.0%、总颜色28.4,其单宁含量和总颜色值与我国林业行业标准LY/T 1325-2012毛杨梅树皮合格品的质量指标相近,具有作为栲胶原料开发利用价值。     

丁二烯适宜贮存温度的研究

研究了贮存温度、时间、气相氧含量和铁锈含量对丁二烯中过氧化物生成量的影响,考察了丁二烯适宜的贮存温度.结果表明:丁二烯中过氧化物含量随着铁锈含量增加而同倍增加;当气相氧含量增加1倍,丁二烯中过氧化物含量提高21%;在对叔丁基邻苯二酚(TBC)为104 mg/kg、贮存时间为7 d条件下,当贮存温度大于21℃时,丁二烯中过氧化物量增加显著;丁二烯较适宜的贮存温度为18℃.工业装置生产运行表明:在18℃下贮存丁二烯是安全、稳定和节能的.将丁二烯贮存温度从13℃调整到18℃,可使其装置运行费用下降43%.     

老榆林酒香味成分贮存变化规律研究

对贮存时间不同、酒度不同老榆林酒的主要香味成分进行了分析测试。研究结果表明,高度酒在贮存过程中相对比较稳定,主要香味成分己酸乙酯、乙酸乙酯、乳酸乙酯均随酒龄增大而减少,相应的酸含量增加;而低度酒在贮存过程中质量变化较大,香味成分随酒度的降低而改变了原有的平衡,酒中酸增加,酯类成分含量下降。     

甲醛缩合法检验落叶松树皮栲胶单宁含量

介绍了甲醛缩合法检验落叶松要树皮栲胶单宁含量的测定方法，与皮粉法对比结果表明，完全可以代替皮粉法的测定，是一种对落叶松树皮栲胶单宁含量测定快速，准确的方法。     

棉花中单宁的提取及含量的测定

本实验采用紫外分光光度法测定了不同产地、不同品级的棉花中单宁的含量,确定了提取及测定棉花中单宁的各项最佳条件。实验结果表明,单宁提取的最佳条件为:液料比为30∶1、温度为85℃、提取时间为60 min;显色的最佳条件为:F-D试剂的用量为0.6 mL、饱和Na2CO3溶液的用量为1.4 mL、显色时间为25 min。     

棉花中单宁的提取及含量的测定

本实验采用紫外分光光度法测定了不同产地、不同品级的棉花中单宁的含量,确定了提取及测定棉花中单宁的各项最佳条件。实验结果表明,单宁提取的最佳条件为：液料比为30∶1、温度为85℃、提取时间为60 min;显色的最佳条件为：F-D试剂的用量为0.6 mL、饱和Na2CO3溶液的用量为1.4 mL、显色时间为25 min。     

纳米碳酸钙影响UF树脂性能的研究

实验对纳米CaCO3对UF树脂固化时间,游离甲醛含量及胶合强度的影响进行研究,结果表明:纳米CaCO3延长了树脂的固化时间,游离甲醛含量随加入量的增加而逐渐减少,纳米CaCO3对胶合板的胶合强度贡献不大。     

值得引种开发利用的经济林木——印度楝

印度楝(Azadirachta indica A.Juss.)又名Melia azadirachta、Melia indica(A.Juss) Brand,俗称neem、neem tree、margosa tree,属楝科(Meliaceae)。原产印度-巴基斯坦次大陆及缅甸。印度楝速生常绿,树高10～20米,直径30～80厘米,树皮灰色、厚,呈鳞片状,内皮粉红色。具收敛性无涩味,树皮单宁含量高。核果,长圆形,13～20毫米长,由淡黄色转变为紫色,果肉带苦味;种核大,椭圆形,内含一粒大籽。树龄四、五年生时,果     

马占相思栲胶浓胶波美度与浓度换算关系及浸提、磺化工艺研究

研究了马占相思栲胶主要生产工序的工艺参数。结果得出：马占相思栲胶浓胶在20 ℃时的波美度（y,°Bé）与浓度（x,kg/L）的关系式为： y=1.2+40x。不同温度（T,℃）下,实测波美度（y’）换算为20 ℃时的波美度（y,°Bé）与温度的关系式为： y=y’+（T-20）/15;浸提工艺：马占相思树皮400 g,吸水率210%,头步加水1 200 mL,以后每步加水800 mL,浸提首罐温度100 ℃,尾罐温度128 ℃,浸提时间12 h,添加焦亚硫酸钠量助浸为气干原料质量的1.8%,栲胶得率为 81.9%,单宁得率为90.6%。磺化工艺：在 85 ℃下,添加焦亚硫酸钠（Na₂S₂O₅）量为栲胶绝干质量的6%,反应时间为 2 h,磺化后得栲胶产品的单宁含量为67.8%,不溶物为3.2%,pH值为4.5,总色度为9.6。其他工艺同杨梅栲胶生产工艺。     

A new source of natural adhesive: Acacia mangium bark extracts co-polymerized with phenol-formaldehyde (PF) for bonding Mempisang (Annonaceae spp.) veneers

Acacia mangium is a fast-growing dicotyledonous tree species and has become the dominating plantation in Malaysia. It was grown particularly as a raw material for veneer, pulp, and paper industries. The chemical properties test in this study showed that the A. mangium tree bark contains higher extractive content as compared to the wood portion (sapwood). Tannin extracts from A. mangium tree bark were found to be rich in phenolic compounds and had the potential to replace conventional phenol-formaldehyde (PF) adhesive used in the plywood manufacturing industry. Tannin adhesive (tannin-paraformaldehyde) prepared from A. mangium bark tannin by cross-linking with paraformaldehyde were used for bonding of Mempisang (Annonaceae spp.) plywood board. However, the resulting bonding strength using tannin adhesive was found to be only suitable for interior grade application. Further extension of its application for interior and exterior grade plywood could be achieved with addition of PF (co-polymerization with resol) during the production process. The optimized formulation of tannin adhesive consists of A. mangium solid extracts (90 parts), commercial PF (10 parts), and paraformaldehyde (3%). Results have shown that the plywood shear strength complies with the requirement for European norms EN 314-1 and EN 314-2:1993, which includes the dry test, cold water test, and the boiling test.     

Application of citric acid as natural adhesive for wood

The development of natural adhesives derived from nonfossil resources is very important for the future. Besides, it is desirable to be safe adhesives without using harmful chemical substances. In this study, application of citric acid as a natural adhesive was investigated. Citric acid powder and bark powder obtained from Acacia mangium were used as raw materials. Citric acid powder was mixed with the bark powder, and the resulting powder mixture was poured into a metal mold. The mold was hot‐pressed at 180°C and 4 MPa for 10 min, and a bark molding was then obtained. The specific modulus of rupture and modulus of elasticity values of the molding containing 20 wt % citric acid were 18.1 MPa and 4.9 GPa, respectively. The molding did not decompose during a repeated boiling treatment. To clarify the effect of tannin on the adhesiveness of molding, bark was separated into tannin and residue. The molding was not obtained while using the tannin due to the marked fluidity, whereas it was obtained while using the residue, the same as while using the bark. It was considered that components other than tannin contributed to the adhesiveness. Based on the results of Fourier transform infrared spectra, the formation of ester linkages between carboxyl groups derived from citric acid and hydroxyl groups in the bark was confirmed. Accordingly, citric acid brought an adhesion by chemical bonding, and it could be used as a safe natural adhesive. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Biodegradable polyurethane materials from bark and starch. I. Highly resilient foams

Liquefaction of the bark of Acacia mearnsii (BK) and cornstarch (CS) was conducted by using a solvent mixture consisting of poly(propylene glycol) (PPG), glycerol, and sulfuric acid with a weight fraction of 94/5/1 at 150°C. Solubilities of BK and CS were about 80% after 60 min and 100% after 20 min in the same solvent, respectively. Highly elastic or highly resilient (HR) polyurethane foams (PUFs) suitable for car‐seat cushions were prepared from the liquefied BK and CS without removing the insoluble residue from the liquefaction mixture. About 20% of the insoluble residue from BK contributed remarkably to the improvement of flame resistance of the resulting PUFs. HR PUFs having better resilience properties were prepared using PPG of molecular weight around 4000, as compared with poly(ethylene glycol) having the same hydroxyl value. PUFs were synthesized from three BKs with different tannin contents, that is, BK0 (tannin: 0%), BK1 (tannin: 43%), and BK2 (tannin: 48.5%), to evaluate the effect of the tannin content on their performance of resilience. Both the resilience value and density of the PUFs increased with increasing BK content for all BK systems. BK2 was chosen to prepare PUFs in the further work. When CS replaced part of BK, the density and compressive strength of the PUFs decreased with an increasing cornstarch proportion, whereas the resilience value had its maximum value when the weight ratio of CS:BK was 1:1. The PUFs were, to some extent, biodegradable: The average weight loss of samples buried in soil for 6 months was 15.6 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2575–2580, 2000     

Development of wood-products adhesives from mangrove bark

Mangrove bark was extracted using either water, ethanol, acetone, or various binary mixtures of these, as solvent. With plywood panels as substrates, joints prepared with adhesives derived from these extracts were tested for strength properties. In terms of the quantity of extracts from mangrove bark, water was the most effective solvent, followed sequentially by ethanol and acetone. However, in terms of the tannin content of these extracts, the order of extraction effectiveness of these solvents was reversed. The use of solvent mixtures in tannin extraction did not produce an observable synergistic effect. The quantity of extract and its tannin content were dictated primarily by the predominant solvent in the binary mixture. The reactivity of mangrove bark extracts is influenced significantly by formaldehyde concentration, cure temperature, type, and pH of the adhesive medium. Adhesive joints of significant bond strength were obtained from mangrove tannin adhesives. Prolonged cure periods, particularly at elevated temperatures, have deleterious effects on the strength properties of these adhesive joints.     

Electrospinning with Condensed Tannins: Effects on Co-spinning with Zein

Abstract

Electrospinning can be applied to renewables creating new materials and applications. We have utilized electrospinning in an attempt to create nanofibers from condensed tannins as well as from binary conjugates formed between this tannin with zein protein. While attempts to directly electrospin pine bark tannin extract proved unsuccessful, combining zein with this tannin gave electrospun fiber from acetic acid and dimethyl formamide (DMF) solutions. To achieve nanofibers possessing significant tannin content, high solids content (≥35%) in DMF solution was required. Electrospun nanofibers (200–400 nm dia.) could be created from zein-tannin combinations with up to 80% tannin content and appropriate solution solids content. Nanofibers could be produced from pre-formed tannin-zein conjugates or via their direct combination as a mixture in the spinning solution. Analysis of thermal stability shows the zein-tannin conjugates have similar thermal properties and stability to zein, being stable up to 240°C.     

Age Variation of Douglas-Fir Bark Chemical Composition

The chemical composition of Douglas-fir bark was analyzed at three stem height levels of trees with different ages from two geographical locations. Cork and phloem in the bark’s rhytidome were analyzed separately at stem bottom: extractives (49.8% and 17.0%, respectively), suberin (30.1% in cork) and hemicelluloses, namely arabinose content (25.3% and. 4.8% of all monomers, respectively). Suberin composition includes α,ω-alkanoic diacids (38.6%), ω-hydroxyalkanoic acids (25.6%), alkanoic acids (18.2%), alkanols (2.2%), and aromatics (8.8%). Bark’s chemical composition is age-related, namely regarding suberin content: at 45, 30 and, 17?years of age, bark contained respectively 25.4%, 2.6%, and 0.9% of suberin; 24.5%, 33.9%, and 29.8% of lignin; and 29.4%, 20.6%, and 25.7% of extractives. This difference is due to the small number of periderms and low cork content in barks with 30 or less years. When aiming at a cork-targeted valorization, the lower stem parts of mature Douglas-fir trees should be considered while the high content of polar extractives at all stem heights allows an overall potential valorization.     

Thermal Degradation of Condensed Tannins from Radiata Pine Bark

Abstract

In order to understand the influence of the inherent chemistry on the relative thermal stability of condensed tannins, the thermal degradation behaviors of various radiata pine bark extracts have been investigated using thermogravimetric analysis (TGA). Generally, results suggest pine bark extract fractions may be readily processed at temperatures below 200°C if co-extracted polysaccharides contents are minimized. Those extracts possessing greater carbohydrate content and lower tannin purity tend to have decreased thermal stability. The initial onset temperature for degradation of relatively crude extracts with high proportions of carbohydrate contents were relatively low (ca. 150°C), whereas extract purification to < 5% carbohydrate content gave increases in thermal stability of at least 50°C. The complicity of the carbohydrate content in the degradation of the tannin samples was also supported by calculated Ozawa activation energies and modulated TGA experiments. While no increase in the thermal stability was gained by acetylating the pendant hydroxyl groups of the pine bark tannin extract, chemical variations such as sulfonation have a large effect on thermal degradation, promoting lower degradation temperatures.